AN Experimental Study on Strengthening of R.C Flat Slab Edge Column Connections Subjected to Punching Shear Due to Eccentric Loads Using FRP

Abstract

During the last few years, the need to flat slab systems has rapidly increased. The slab column connections behavior plays decisive role because of the sudden expected brittle failure as the slab may be punched by column, so improving the behavior of these connections is essential. Flat slab column connections can benefit from being strengthened by fiber reinforced polymers (FRP) as a structural application in punching shear [1]. The effect of using carbon fiber (CFRP) and glass fiber (GFRP) was investigated experimentally, also steel reinforcement bars were utilized as strengthening element for comparison. Results of tested fifteen half-scale flat slab-edge column connections reinforced concrete specimens under eccentric loads were obtained. The investigated parameters were the eccentricity value, the type of strengthening material and the number of rows of strengthening elements. Five groups were created from the fifteen tested specimens, every one contained three specimens. The first group consisted of three non-strengthening specimens, with variable eccentricity values (0, e & 2e), these specimens were considered as control ones. Each of the other four groups consisted of three specimens, which were strengthened by CFRP, GFRP and steel bars. All the specimens of the second and fourth groups were strengthened by one row of strengthening elements. All the specimens of the third and fifth groups were strengthened by two rows of strengthening elements. The second and third groups were loaded with the eccentricity value (e) while the fourth and fifth groups were loaded with the eccentricity value (2e). According to the test results, punching shear resistance increased up to 82 %. Also, the ductility factor results revealed improvement of up to 50%. Ultimate loads were predicted according to ACI 440, and the calculated values shown good agreement with the experimental ones.